KR20080046635A - Fluid bearing device, method of manufacturing the same, and disk drive device - Google Patents

Abstract

[PROBLEMS] To provide a fluid bearing device with a hub part having high molding accuracy and dimensional stability and manufacturable at low cost. [MEANS FOR SOLVING THE PROBLEMS] An annular gate (14) is formed at the portion of a cavity (15) corresponding to the lower end face (10c1) outer diameter end part of a flange part (10c), and a molten resin (P) is filled into the cavity (15) through the annular gate (14) to form the resin hub part (10). The hub part (10) molded by the injection molding comprises a radial resin orientation through all the periphery thereof. Furthermore, an annular gate trace (16) is formed at the lower end face (10c1) outer diameter end part of the flange part (10c) of the hub part (10).

Description

FLUID BEARING DEVICE, METHOD OF MANUFACTURING THE SAME, AND DISK DRIVE DEVICE

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid bearing device for supporting a shaft member rotatably in the radial direction with a lubricating film of fluid generated in the radial bearing gap, a manufacturing method thereof, and a disk drive device having the fluid bearing device. Examples of the disk driving apparatus include magnetic disk driving apparatuses such as HDDs, optical disk driving apparatuses such as CD-ROM, CD-R / RW, DVD-ROM / RAM, and magneto-optical disk driving apparatuses such as MD and MO. The fluid bearing device of the present invention can also be suitably used for small motors such as information devices other than the disk drive device, for example, a polygon scanner motor of a laser beam printer (LBP), a color wheel motor of a projector, or a fan motor.

The various motors are required to have high speed, low cost, low noise, etc. in addition to high speed rotation accuracy. One of the components that determine these required performances is a bearing for supporting the spindle of the motor. In recent years, the use of a fluid bearing having characteristics excellent in the required performance has been examined and actually used.

This kind of fluid bearing is divided into a dynamic bearing having a dynamic pressure generating portion for generating dynamic pressure in the lubricating fluid in the bearing clearance, and a so-called cylindrical bearing (a bearing having a circular bearing section) having no dynamic pressure generating portion. Lose.

For example, in a fluid bearing device assembled to a spindle motor of a disk drive device such as an HDD, both a radial bearing part supporting the shaft member in the radial direction and a thrust bearing part supporting in the thrust direction may be constituted by dynamic pressure bearings. . As the radial bearing portion in this type of fluid bearing device (dynamic bearing device), for example, a dynamic pressure groove as a dynamic pressure generating portion is formed on either of the inner circumferential surface of the bearing sleeve and the outer circumferential surface of the shaft member opposite thereto. It is known to form a radial bearing clearance between both surfaces (for example, refer patent document 1).

Further, when the fluid bearing device is assembled and used in a disk drive device motor such as an HDD, a hub is provided on the shaft member, and an information storage medium such as a magnetic disk is loaded or held on an end surface of the hub (for example, a patent). See Document 2. A yoke made of a magnetic body for improving the magnetic efficiency between the rotor magnet and the stator coil is usually fixed at a position of the disk hub opposite the stator coil provided on the stationary side of the motor. As a means for fixing this kind of yoke to the disk hub, a means using, for example, an adhesive is known.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2003-239951

[Patent Document 2] Japanese Unexamined Patent Publication No. 2005-45924

However, in recent years, a number of proposals have been made to reduce the manufacturing cost of the fluid bearing device in response to the demand for lowering the cost of information equipment. For example, the resin component of the said fluid bearing device, such as a hub, is aimed at reducing material cost.

However, when forming the hub, for example, depending on the shape of the gate and the position of the gate filling the molten resin in the cavity, the molding precision of the hub may be lowered, whereby the following required characteristics for the hub may not be satisfied. .

As an example, when injection molding the hub 20 of the shape shown in FIG. 12 with resin, as shown in FIG. 13 and FIG. 14, of the hub 20 of the shaping | molding die (not shown) which has the cavity 21 is shown. A plurality of point gates 22 (three places at equal intervals in the circumferential direction in the illustrated example) are formed at positions corresponding to one end surface 20a, and from the plurality of point gates 22, the cavity 21 is formed. ), A method of filling the molten resin (P) is considered. However, in this method, the molten resin P sent out from each point gate 22 into the cavity 21 flows from each point gate 22 toward the circumferential direction (direction of arrow in FIG. 13), respectively. Join at the intermediate position 23 between the point gates 22 and 22. Therefore, the flow direction of the molten resin P joined from both circumferential directions fluctuates radially from the circumferential direction at the intermediate position 23. Thereby, the resin molded article (hub 20) after solidification forms the form which made the orientation state (molecular orientation) of resin different from the other circumferential direction in the intermediate position 23 correspondence place.

In this case, the amount of shrinkage of the molding becomes irregular in the circumferential direction, and there is a concern that the geometric accuracy of the surface where high dimensional accuracy is required, for example, a disk mounting surface. In addition, when the fluid bearing device having the hub is used, since the amount of dimensional change of the hub due to the temperature change is different in the circumferential direction, this lowers the fixing accuracy (perpendicularity or coaxiality) with respect to the shaft member of the hub, There is a possibility that the rotational accuracy is adversely affected.

In addition, after the molten resin in the cavity is cooled and solidified, the molten resin is taken out of the molding die by performing die opening of the molding die. The molded article is in a form connected to the gate solidification portion formed in the gate in the state before the die opening, but the gate solidification portion is divided by performing die opening, and a part of the gate solidification portion remains on the molded article side as a gate mark. Therefore, depending on the size and shape of the gate mark (gate solidification part) remaining on the molded product side, after forming, for example, cutting is performed to remove the gate solidification part from the molded product.

In the gate solidification part which consists of these gate marks, and the gate removal mark which remain | survives on the molded article side after the removal process of the gate solidification part, the cut surface formed at the time of a gate cut, or the removal process surface formed at the time of removal process exists. Unlike the molded surface, these divided surfaces and the removed surface are exposed to the inner end surface of the resin molded article, so that the filler blended in the resin material is partially exposed, for example, so that the filler and the like can easily fall off. . The dropped filler or the like is adhered to the surface of the housing or the like, and there is a fear of being mixed as a contaminant in the lubricating oil filled inside the bearing device when the bearing device is assembled. In particular, contaminants generated around the disk hub are undesirable because they adhere to the surface of the disk and may degrade the read accuracy of the disk.

In addition, in a disk drive device such as an HDD, in order to obtain high disk reading accuracy, the dimensional accuracy of the hub holding the disk, and more precisely, the dimensional precision of the disk mounting surface on which the disk is loaded is important. If only high precision of the disk mounting surface is to be achieved, high precision processing of the disk mounting surface may be performed separately.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fluid bearing device capable of manufacturing a hub having high molding accuracy and dimensional stability at low cost and a method of manufacturing the same.

Another object of the present invention is to provide a fluid bearing device which can be manufactured at low cost and which also has high cleanliness.

In order to solve the above problems, the present invention provides a radial direction of the shaft member with a lubricating film of the shaft member, a hub portion integrally or separately provided to the shaft member, and a lubricating film formed in the radial bearing gap facing the outer circumferential surface of the shaft member. A radial bearing portion for supporting relative rotation is provided, wherein the hub portion is formed of a resin, and the hub portion exhibits a resin orientation in the radial direction over its entire circumference.

In this way, if the hub portion exhibits the resin orientation in the radial direction at any position in the circumferential direction, the shrinkage direction at the time of molding does not become irregular in the circumferential direction, so that such molding shrinkage can be generated as evenly as possible. In addition, irregularities in the circumferential direction of the dimensional change amount due to temperature change are also suppressed as much as possible. Therefore, it is possible to provide a fluid bearing device having high rotational accuracy by securing dimensional accuracy (planar view, etc.) necessary for the hub portion, and high fixing accuracy (perpendicularity, etc.) with respect to the shaft member.

In addition, in order to solve the above problems, the present invention uses a shaft member, a hub portion which is integrally or separately provided to the shaft member, and a shaft member with a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member. A radial bearing portion for supporting relative rotation in the radial direction is provided, wherein the hub portion is injection molded with a resin, and an annular gate mark is formed in the hub portion by injection molding to provide a fluid bearing device. do. Here, the gate mark indicates a position where the gate position when filling the molten resin into the molding die during injection molding of the bearing member can be determined from the molded article, and the gate cut among resins solidified inside the gate during injection molding, for example. It also includes a portion remaining on the surface of the molded article. Or a gate removing mark formed when the remaining portion is removed by machining or the like.

In addition, in order to solve the above problems, the present invention uses a shaft member, a hub portion which is integrally or separately provided to the shaft member, and a shaft member with a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member. A method of manufacturing a fluid bearing device having a radial bearing portion that supports relative rotation in a radial direction, the method comprising: an injection molding step of injection molding a hub part with a resin, and having an annular shape in a molding die of the hub part in an injection molding step. A method of manufacturing a fluid bearing device is provided, comprising forming a gate and filling molten resin into a cavity from an annular gate.

During injection molding, since the molten resin is filled in the cavity from the entire circumference of the circumferential direction through the annular gate, the molded article (hub portion) after solidification exhibits a resin orientation in the radial direction almost at least when viewed from the circumferential direction, whereby Molding shrinkage of the hub portion can be generated more evenly in the radial direction.

When the fluid bearing device is assembled to a disk drive motor such as an HDD, the hub bearing surface is formed in the hub portion, and in this case, the gate mark is preferably formed near the disk mounting surface. According to this structure, since the molten resin is filled in the state where the gate is arranged near the disk mounting surface during injection molding, the area corresponding to the disk mounting surface of the cavity can be filled with a high injection pressure. have. Therefore, the molding shrinkage amount in the said location can be reduced and dimensional accuracy can be improved.

Moreover, in the injection molding process of the hub portion according to the present invention, it is preferable to perform injection molding using an annular gate whose gate width is different in the circumferential direction. Usually, in this kind of injection molding, a spool or runner is provided between a nozzle of an injection machine for injecting molten resin and a gate open to the cavity of the molding die, and the molten resin injected from the nozzle is a branch of the spool or runner. The gate is reached via. Therefore, even when the annular gate is formed, the molten resin is not simultaneously sent out into the cavity from the entire circumference of the gate at the same time, and some time lugs may occur. The present invention has been made in view of this point, and, for example, in the annular gate, for example, the gate width of the side where the distance to the injection nozzle (the flow length of the molten resin) is far is increased, and the side facing the injection nozzle (to the injection nozzle) is increased. The problem caused by the time lugs mentioned above can be improved by reducing the gate width of the side (near the distance). Therefore, the molded article (hub part) which shows the more uniform resin orientation by generating the flow of resin which goes to radial direction in a cavity uniformly over the perimeter.

In addition, in order to solve the above problems, the present invention uses a shaft member, a hub portion which is integrally or separately provided to the shaft member, and a shaft member with a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member. A radial bearing portion for supporting relative rotation in the radial direction and a yoke made of a magnetic body and adhesively fixed to the hub portion, wherein the hub portion is injection molded with resin and formed in the hub portion by injection molding. It provides a fluid bearing device characterized in that the gate mark is blocked by the adhesive supplied to the adhesive fixing surface of the hub portion and the yoke.

In addition, in order to solve the above problems, the present invention uses a shaft member, a hub portion which is integrally or separately provided to the shaft member, and a shaft member with a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member. A method of manufacturing a fluid bearing device comprising a radial bearing portion for supporting relative rotation in a radial direction and a yoke made of a magnetic body and adhesively fixed to the hub portion, the injection molding process of injection molding the hub portion with a resin; And an adhesive fixing step of adhesively fixing the yoke to the hub portion formed in the injection molding process, wherein the gate mark formed by injection molding of the hub portion in the adhesive fixing step is applied to the adhesive supplied to the adhesive fixing surface of the hub portion and the yoke. Provided is a method for producing a fluid bearing device, wherein the adhesive is solidified in a closed state.

In this way, the gate mark formed on the surface of the hub portion by injection molding of the resin is blocked by an adhesive supplied to the adhesive fixing surface of the hub portion and the yoke, so that the gate mark is external after the adhesion fixing of the hub portion and the yoke. It becomes the state sealed with respect to space (outer air). Therefore, it is possible to improve the cleanliness of the bearing device and its surroundings by avoiding the situation in which fillers or the like fall off and adhere to the inside and the surroundings of the bearing device as contaminants from the gate mark (gate solidifying part or gate removing mark).

According to this configuration, the gate mark is closed in accordance with the adhesive fixing of the hub portion and the yoke. Therefore, only the yoke, which is a component of the fluid bearing device, and the adhesive used for adhesive fixing of the yoke are sufficient to close the gate mark, and a step for blocking the gate mark separately in addition to the injection molding process or the adhesive fixing process of the hub portion is provided. No need to add Therefore, such a clogging operation can be performed without causing an increase in cost.

More preferably, the gate mark is on the adhesive fixing surface with the yoke. According to such a structure, since a gate mark is reliably sealed by the adhesive agent supplied between the adhesive fixing surface of a yoke and a hub part, generation | occurrence | production of the contaminant from a gate mark can be prevented more reliably.

Moreover, in order to solve the said subject, this invention is a rotating member which has a shaft part and the hub part integrally or separately installed in the shaft part, and the rotating member by the dynamic pressure action of the fluid which arises in the radial bearing gap which the outer peripheral surface of a shaft part faces. Pressure bearing device including a radial bearing part for rotatably supporting the bearing in a radial direction, non-contacting contact with the disk mounting surface of the hub part, a disk fixed by a predetermined clamping force, and a disk-mounted rotation. A disk drive apparatus having a motor portion for rotatingly driving a member, wherein the disk mounting surface is deformed by imitating a contact surface of the disk by a clamping force.

According to this configuration, when the disk is fixed, the disk mounting surface of the hub portion is corrected by the contact surface of the disk. For this purpose, by using a disk having such a contact surface finished with high accuracy, the dimensional accuracy of the disk mounting surface can be increased to the dimensional accuracy level of the disk without performing a special high precision processing. In particular, magnetic disks used in HDDs and the like are usually finished with high precision in order to increase the reading accuracy by the disk head. Therefore, by using this type of disk, the dimensional accuracy of the disk mounting surface can be easily and at low cost. Can be improved. Therefore, the disk can be fixed to the hub portion by maintaining a high perpendicularity to the shaft portion (rotation shaft), whereby the vibration accuracy of the disk during rotation can be improved.

In this case, it is preferable that the area | region containing a disk mounting surface is shape | molded with resin. Since resins are generally less rigid than other materials (metals or ceramics), they are also dependent on the thickness in the clamp direction, but the disk mounting surface can be easily modified to mimic the contact surface of the disk. Therefore, the disk mounting surface which makes both dimensional precision and processing cost to a high level can be obtained by shape | molding focusing on moldability (cycle time etc.) rather than dimensional precision at the time of shaping | molding.

Effect of the Invention

As mentioned above, according to this invention, the fluid bearing apparatus which can manufacture the hub which has high molding precision and dimensional stability at low cost, and its manufacturing method can be provided.

Further, according to the present invention, it is possible to provide a fluid bearing device which can be manufactured at low cost and has high cleanliness.

Moreover, according to this invention, the disk drive apparatus provided with the hub part which has high dimensional precision can be provided at low cost.

1 is a cross-sectional view of a spindle motor incorporating a fluid bearing device according to an embodiment of the present invention.

2 is a cross-sectional view of the fluid bearing device.

3 is a longitudinal sectional view of the sleeve portion.

4 is a bottom view of the sleeve portion.

5 is a cross-sectional view of the housing portion viewed from the direction of arrow A. FIG.

6 is a diagram conceptually illustrating an injection molding process of a hub portion using an annular gate.

It is a figure which shows notionally the flow of molten resin in a cavity when an annular gate is used.

8 is an enlarged cross-sectional view showing the periphery of the gate mark of the hub portion.

9 is an enlarged cross-sectional view showing the periphery of the adhesive fixing surface of the hub portion and the yoke.

10 is an enlarged cross-sectional view showing the periphery of a gate mark according to another embodiment.

FIG. 11 is a cross-sectional view of the disk drive device in which the disk D is mounted on the spindle motor shown in FIG. 1.

It is sectional drawing which shows one form of hub part.

It is a figure which shows notionally the flow of molten resin in a cavity when a point gate is used.

14 is a view conceptually illustrating an injection molding process of a hub portion using a point gate.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on drawing.

Fig. 1 conceptually shows an example of the configuration of a spindle motor for an information apparatus incorporating a fluid bearing device 1 according to an embodiment of the present invention. This spindle motor is used in a disk drive device such as an HDD, and is a fluid bearing device (dynamic bearing device) for non-contactably supporting the rotating member 3 having the shaft member 2 and the hub portion 10 in a relatively rotatable manner ( 1), the stator coil 4, the rotor magnet 5, and the bracket 6 which faced through the radial gap, for example are provided. The stator coil 4 is attached to the bracket 6, and the rotor magnet 5 is fixed to the hub portion 10 via the yoke 12. The bearing member 7 of the fluid bearing device 1 is fixed to the inner circumference of the bracket 6. Although not shown, the hub portion 10 holds one or a plurality of disks as information recording media. In the spindle motor configured as described above, when the stator coil 4 is energized, the rotor magnet 5 is rotated by an excitation force generated between the stator coil 4 and the rotor magnet 5, and with this, The hub portion 10 and the disk held in the hub portion 10 are rotated integrally with the shaft member 2.

2 shows a fluid bearing device 1. The fluid bearing device 1 is rotated relative to the bearing member 7, the lid member 11 closing one end of the bearing member 7, and the bearing member 7 and the lid member 11. The rotating member 3 is mainly provided. In addition, for convenience of explanation, it demonstrates below, with the side closed by the cover member 11 among the opening parts of the bearing member 7 formed in the axial end both on the lower side, and the side opposite to the closed side.

The bearing member 7 has a shape which is open at both ends in the axial direction, and is located on the outer cylindrical side of the substantially cylindrical sleeve portion 8 and the sleeve portion 8 and is formed integrally or separately from the sleeve portion 8. The part 9 is provided.

The sleeve portion 8 is formed in a cylindrical shape by, for example, a porous body made of a metal nonporous body or a sintered metal. In this embodiment, the sleeve portion 8 is formed in a cylindrical shape with a porous body of sintered metal mainly composed of copper, and adhered to the inner circumferential surface 9c of the housing portion 9 (including loose adhesion). , By press fitting (including press bonding), welding (including ultrasonic welding), or the like. Of course, it is also possible to form the sleeve part 8 with materials other than metal, such as resin and a ceramic.

A region in which a plurality of dynamic pressure grooves are arranged as a radial dynamic pressure generating portion is formed on the entire surface or a part of the cylindrical region of the inner circumferential surface 8a of the sleeve portion 8. In this embodiment, as shown, for example in FIG. 3, the area | region which arranged the several dynamic pressure grooves 8a1 and 8a2 in the herringbone shape is spaced apart in the axial direction, and is formed in two places.

A thrust dynamic pressure generating portion, for example, as shown in FIG. 4, is provided with a region in which a plurality of dynamic pressure grooves 8b1 are arranged in a spiral shape on the entire surface or part of the annular region of the lower end surface 8b of the sleeve portion 8. .

The housing part 9 is formed in a substantially cylindrical shape with a metal or resin. In this embodiment, the housing part 9 forms the shape which opened the both ends of the axial direction, and the one end side is sealed by the cover member 11. A thrust dynamic pressure generating portion, for example, as shown in FIG. 5, is provided with a spiral arrangement of a plurality of dynamic pressure grooves 9 a1 in a spiral shape on the entire surface or part of the annular region of the end surface (upper surface) 9a on the other end side. . On the outer periphery of the upper part of the housing part 9 (end periphery on the side of the upper end face 9a), an annular tapered surface 9b gradually expanding upward is formed.

The cover member 11 which seals the lower end side of the housing part 9 is formed of metal or resin, and is fixed to the step part 9d formed in the lower inner peripheral side of the housing part 9. Here, the fixing means is not particularly limited, and the combination of materials or required fixing strength may be achieved by, for example, bonding (including loose bonding or press bonding), pressing, welding (such as ultrasonic welding), welding (such as laser welding), or the like. It can select suitably according to sealing property.

In this embodiment, the rotating member 3 is provided on the shaft member 2 inserted into the inner circumference of the sleeve part 8, the upper end of the shaft member 2, and is arrange | positioned at the opening side of the bearing member 7; The hub portion 10 is mainly provided.

The shaft member 2 is made of metal in this embodiment, and is formed separately from the hub portion 10. The outer circumferential surface 2a of the shaft member 2 is formed with dynamic pressure grooves 8a1 and 8a2 formed in the inner circumferential surface 8a of the sleeve portion 8 in a state where the shaft member 2 is inserted into the inner circumference of the sleeve portion 8. It is opposed to the area. The outer circumferential surface 2a has a radial bearing gap between the first and second radial bearing portions R1 and R2 described later between the dynamic member grooves 8a1 and 8a2 when the shaft member 2 rotates. Are formed respectively (see FIG. 2).

At the lower end of the shaft member 2, the flange portion 2b is provided separately as a fall prevention. The flange portion 2b is made of metal and is fixed to the shaft member 2 by, for example, screwing or the like. The upper surface 2b1 of the flange portion 2b is opposed to the dynamic pressure groove 8b1 forming region formed in the lower surface 8b of the sleeve portion 8, and the dynamic pressure groove 8b1 is rotated when the shaft member 2 rotates. The thrust bearing clearance of the 1st thrust bearing part T1 mentioned later is formed between formation area (refer FIG. 2). Moreover, the recessed part (annular groove in this embodiment) 2c is formed in the upper end of the shaft member 2. This recessed part 2c is the shaft member 2 with respect to the hub part 10, when forming the hub part 10 by injection molding of resin which makes the shaft member 2 into an insert part, as mentioned later. It acts as a fallout prevention.

The hub portion 10 includes a disk portion 10a covering the opening side (upper side) of the bearing member 7, a cylindrical portion 10b extending downward in the axial direction from the outer peripheral portion of the disk portion 10a, and a cylindrical shape. The flange part 10c which protrudes from the part 10b to the outer diameter side, and the disk mounting surface 10d formed in the upper end of the flange part 10c are provided. The disk, not shown, is fitted from the outside to the outer periphery of the disc 10a, and is loaded on the disk mounting surface 10d. Then, the disk is held in the hub portion 10 by appropriate holding means (not shown).

The lower surface 10a1 of the disk portion 10a is opposed to the upper surface 9a (dynamic pressure groove 9a1 forming region) provided at one end of the housing portion 9, and when the shaft member 2 is rotated, The thrust bearing clearance of the 2nd thrust bearing part T2 mentioned later is formed between the dynamic-pressure groove 9a1 formation area | region (refer FIG. 2).

The inner circumferential surface 10b1 of the cylindrical portion 10b is opposed to the tapered surface 9b provided on the outer circumferential upper end of the housing portion 9, and the radial dimension gradually contracts upward between the tapered surface 9b. A tapered seal space S is formed. In the state where the lubricating oil mentioned later is filled in the fluid bearing apparatus 1 inside, the oil surface of lubricating oil is always in the range of the seal space S. As shown in FIG.

The hub portion 10 having the above-described configuration is molded by injection molding of a resin composition containing, for example, a crystalline resin such as LCP, PPS, PEEK, or an amorphous resin such as PPSU, PES, or PEI as a base resin. In this embodiment, the hub part 10 which integrally provided the shaft member 2 is shape | molded by injection molding using the shaft member 2 as an insertion component. Further, fillers that can be blended with the resin include, for example, fibrous fillers such as carbon fibers and glass fibers, whisker fillers such as potassium titanate, flaky fillers such as mica, carbon black, graphite, and carbon nanomaterials. And conductive fillers such as various metal powders. These fillers are mix | blended with the said base resin suitably according to the objective, such as reinforcement of the hub part 10 and provision of electroconductivity.

Hereinafter, an example of the injection molding process of the hub part 10 is demonstrated.

FIG. 6 conceptually illustrates the injection molding process of the hub portion 10. The molding die (not shown in the drawing), which is composed of a fixed type and a movable type, includes a runner 13, an annular gate 14, and a cavity 15. ) Is installed. The annular gate 14 is a film gate in this embodiment, and is formed at the position (refer FIG. 2) corresponding to the outer peripheral edge part of the lower end surface 10c1 of the flange part 10c of a shaping | molding die. Here, the gate width of the annular gate 14 is constant over its entire circumference. In addition, at the time of injection molding of the hub part 10, the shaft member 2 is arrange | positioned at the predetermined position in the shaping | molding die (cavity 15) as an insertion part.

The molten resin P injected from the nozzle of the injection molding machine (not shown) is filled into the cavity 15 through the runner 13 and the annular gate 14 of the molding die. In this way, the molten resin P is filled in the cavity 15 from the annular gate 14 formed at a position corresponding to the outer diameter end portion of the lower end surface 10c1 of the flange portion 10c of the hub portion 10, and FIG. As shown in FIG. 7, molten resin P is equally filled in the cavity 15 from the whole perimeter. Thereby, the hub part 10 which has high shaping | molding dimension precision and shows the same resin orientation in the radial direction over the perimeter can be obtained.

In addition, in this embodiment, since the annular gate 14 was formed in the position corresponding to the vicinity of the disk mounting surface 10d of the cavity 15, the annular gate 14 is made into the cylindrical part of the cavity 15, for example. As compared with the case where it is formed in the location corresponding to the surface (10b) etc., the flange part 10c containing the disk mounting surface 10d can be shape | molded in the state which maintained high injection pressure. Thereby, the hub part 10 which improved the shaping | molding precision (planar view etc.) of the disk mounting surface 10d can be obtained.

After the molten resin P filled in the cavity 15 is solidified, the mold die is opened to take out the hub portion 10 integrally formed with the shaft member 2. With the die opening, the gate solidification portion formed in the annular gate 14 is automatically cut (or the gate solidification portion is cut by the gate cut mechanism), and a portion of the gate solidification portion is annular at the gate corresponding position of the hub portion 10. It remains as the gate mark 16 of.

In this embodiment, this gate mark 16 is removed by machining etc. to the position of X in FIG. 8, for example. As a result, most of the gate mark 16 is removed, and the gate removal mark as part of the gate mark 16 remains at the outer diameter end of the lower surface 10c1.

The rotating member 3 is completed by adhesively fixing the yoke 12 made of, for example, a magnetic body to the hub portion 10 formed as described above.

The yoke 12 is an annular member having an approximately L-shaped cross section in this embodiment, and has an inner cylinder portion 12a and an outer diameter protrusion 12b projecting from one end of the inner cylinder portion 12a to the outer diameter side. The outer diameter projecting portion 12b is lower than the inner diameter side of the rotor magnet 5 fixed to the yoke 12 here in order to adjust the axial position with respect to the stator coil 4. The other end side of the cylinder part 12a) is displaced. Therefore, as will be described later, the upper end surface 12b1 of the outer diameter projecting portion 12b is in contact with the hub portion 10 at its inner diameter side, and the lower end surface 12b2 is connected to the rotor magnet 5 at its outer diameter side. Contact.

The work of fixing the yoke 12 of the above configuration to the hub portion 10 is performed as follows, for example.

The adhesive agent 13 is previously apply | coated to the outer peripheral surface 10b2 of the cylindrical part 10b used as the adhesive fixing surface with the yoke 12, or the lower end surface 10c1 of the flange part 10c. And the yoke 12 is inserted in the outer periphery of the cylindrical part 10b of the hub part 10 in the state which arrange | positioned the outer diameter protrusion part 12b on the upper side, and the upper end surface (of the outer diameter protrusion part 12b ( 12b1) is pressed against the bottom surface 10c1 of the flange portion 10c. Thereby, the adhesive agent 13 previously apply | coated to the lower surface 10c1 spreads around from the application area | region, for example, as shown in FIG. 9, the gate mark 16 by the adhesive agent 13 extruded to the outer diameter side. Part of the (gate removal mark) is sealed. Therefore, in this embodiment, a part of the inner diameter side of the gate mark 16 (gate removal mark) is between the adhesive fixing surface (upper end surface 12b1 and lower end surface 10c1) of the hub portion 10 and the yoke 12. It is sealed (closed) by the adhesive 13 which exists, and the remainder (outer diameter side) is sealed (closed) by the adhesive 13 extruded from the adhesive fixing surface.

It heats in this state, and the adhesive fixing work of the hub part 10 and the yoke 12 is completed by solidifying the adhesive agent 13.

In this way, the adhesive part is fixed in a state in which the gate mark 16 of the hub portion 10 is blocked by the adhesive 13 applied to the bottom surface 10c1 of the hub portion 10, in other words, the hub portion In the injection molding of (10), the hub portion 10 is formed in a region which becomes the adhesive fixing surface of the hub portion 10 and the yoke 12 or in an area where the adhesive 13 spreads on the same plane as the adhesive fixing surface. By forming the gate 17, the gate mark 16 (gate removing mark) is sealed to the external space (outside air). As a result, the fluid bearing device 1 and the motor are prevented from being removed from the surface of the gate mark 16 (gate removal mark) by the filler or the like as a contaminant. You can increase the cleanliness of the surroundings.

In addition, since the closing operation | movement of the gate mark 16 is performed simultaneously with the adhesive fixation of the hub part 10 and the yoke 12, what is other than the yoke 12 and the adhesive agent 13 in closing the gate mark 16 It is unnecessary, and it is not necessary to add a process for closing the gate mark 16 before and after the adhesion fixing step. Therefore, the hub portion 10 (fluid bearing device 1) can be manufactured without incurring an increase in cost.

Various lubricants can be used as the lubricating oil filled in the fluid bearing device 1, but the lubricating oil provided to the fluid bearing device for a disk drive device such as an HDD can be stored in consideration of the temperature change during its use or transportation. Ester lubricating oil excellent in evaporation rate and low viscosity, such as dioctyl sebacate (DOS), dioctyl azelate (DOZ), etc. can be used preferably.

In the fluid bearing device 1 having the above-described configuration, when the shaft member 2 is rotated, the dynamic pressure grooves 8a1 and 8a2 formed in the inner circumferential surface 8a of the sleeve 8 are formed of the opposite shaft member 2. A radial bearing gap is formed between the outer circumferential surface 2a. As the shaft member 2 rotates, the lubricating oil in the radial bearing gap is press-fitted to the axial center side of the dynamic pressure grooves 8a1 and 8a2, and the pressure thereof is increased. In this way, the first radial bearing portion R1 and the second radial bearing portion R2 for non-contacting support of the shaft member 2 in the radial direction by the dynamic pressure action of the lubricating oil generated by the dynamic pressure grooves 8a1 and 8a2. Are each configured.

At the same time, the thrust bearing clearance between the lower end surface 8b (dynamic pressure groove 8b1 forming area) of the sleeve part 8 and the upper end surface 2b1 of the flange part 2b opposite to this, and the housing part ( The pressure of the lubricating oil film formed in the thrust bearing gap between the dynamic pressure groove 9a1 formation region formed in the upper end surface 9a of 9) and the lower surface 10a1 of the hub portion 10 opposite thereto is equal to the dynamic pressure groove 8b1. It becomes high by the dynamic pressure action of (9a1). And the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 which support the rotating member 3 (hub part 10) non-contactingly in thrust direction by the pressure of these oil films are comprised, respectively.

FIG. 11 shows the disk drive device HDD having the disk D mounted on the spindle motor shown in FIG. 1. Sub-assy of the disc drive device is completed by fixing the yoke 12 made of magnetic material, the rotor magnet 5, and the disc D to the hub portion 10, for example. Hereinafter, the fixing operation of the disk D to the hub portion 10 will be described.

First, the lower surface D1 of the disk D serving as a contact surface is fitted by fitting the cylindrical surface 10e formed on the outer periphery of the cylindrical portion 10b to the hole D2 formed in the center of the disk D. Contact with (10d). From this state, for example, the clamper 13 shown in FIG. 11 is mounted from the bearing inner side opposite to the hub portion 10, and the disk D is fastened by fastening the clamper 13 to the shaft portion 2 with the screw 14. Is clamped to receive the clamping force from the clamper 13 and the hub portion 10 is fixed.

At the same time, the disk mounting surface 10d of the hub portion 10 receives a pressing force from the lower surface (contact surface d1) of the disk D. FIG. As a result, the disk mounting surface 10d is deformed to mimic the lower surface D1, and the disk mounting surface 10d is corrected by the lower surface D1 of the disk D. FIG. Therefore, even if the dimensional precision at the time of molding the resin hub portion 10 (disk mounting surface 10d) is not so high, the dimensional precision of such disk mounting surface 10d is accompanied by the fixing of the disk D. It can improve to the level equivalent to the dimensional precision of lower surface D1. Therefore, the disk D can be fixed on the disk mounting surface 10d in a state where the perpendicularity with respect to the shaft portion 2 is maintained at a high level.

In addition, as in this embodiment, by forming the region including the disk mounting surface 10d with resin, the side of the disk mounting surface 10d is easily responded to the pressure from the disk D usually formed of aluminum or glass. Can be deformed by imitating the contact surface D1 of the disk D.

Therefore, the disk D rotates while maintaining a high perpendicularity to the shaft portion 2 (rotating shaft), whereby the vibration accuracy of the disk D during rotation is improved. Therefore, the reading accuracy of the disk D can be improved by maintaining the opposing interval with the disk head with high accuracy.

In this case, the disk D rotates while maintaining a high right angle with respect to the shaft portion 2 (rotating shaft), whereby the vibration accuracy of the disk D during rotation is improved. Therefore, the reading accuracy of the disk D can be improved by maintaining the opposing interval with the disk head with high accuracy.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this embodiment, Various deformation | transformation illustrated below is possible.

In the above embodiment, the case where the gate mark 16 (gate removing mark) is formed at the outer diameter end (chamfered part) of the lower end surface 10c1 of the flange portion 10c has been described, but the gate mark 16 is a hub portion. (10) It can be formed in arbitrary places of the hub part 10 as long as it is formed ring-shapedly connected to the surface.

For example, in the hub part 10 shown in FIG. 2, the lower end surface 10c1, the outer peripheral surface 10c2 of the flange part 10c, the inner and outer peripheral surfaces 10b1, 10b2 of the cylindrical part 10b, or the disk part ( Points corresponding to the gate mark 16 (in other words, the bottom surface 10c1 or the outer circumferential surface 10b2 of the cavity 15) in approximately the entire area of the upper surface 10a2 (including the chamfered portion of the outer circumferential end) of 10a. It is also possible to form the gate 14 in the.

Alternatively, even in the case where the gate mark 16 is not directly sealed by the adhesive 13, there are regions around the hub portion 10 and the yoke 12 that are adhesively fixed by the adhesive 13. The gate mark 16 should just be indirectly sealed by the adhesive agent 13 from external air (outer space). For example, FIG. 10 shows an example, and the gate mark 16 is formed in the vicinity of the attachment of the cylindrical part 10b and the flange part 10c of the hub part 10, and the flange part 10c in the outer diameter side. The bottom surface 10c1 of and the top surface 12b1 of the outer diameter protrusion 12b of the yoke 12 are adhesively fixed by the adhesive agent 13. Moreover, below the gate mark 16, the outer peripheral surface 10b2 of the cylindrical part 10b and the inner peripheral surface 12a1 of the inner side cylinder part 12a are adhesively fixed by the adhesive agent 13. As shown in FIG.

Moreover, although the case where the gate width was uniform was used for the annular gate 14 used for the injection molding of the hub part 10 in the circumferential direction was illustrated in the said embodiment, it is not limited to this, For example, a gate width is circumferential direction, for example. Other annular gates 14 may be used. In this case, for example, it is preferable to increase the gate width of the location where the flow path distance to the nozzle of the injection machine (not shown) is the largest and to decrease the gate width of the location where the flow path distance to the nozzle is the smallest. As shown in Fig. 7, the outer circumferential surface of the cylindrical annular gate 14 shown in the figure is moved radially to deviate the outer circumferential surface of the annular gate 14 with respect to the inner circumferential surface, whereby the gate width can be made different in the circumferential direction. have.

In addition, although the gate mark 16 was removed in the said embodiment in order to avoid contact with another member (for example, the yoke 12 or a disk), the gate mark 16 does not contact these other members, Or if it does not matter in particular even if it contacts, you may not need to perform a removal process.

Although the case where the hub part 10 which has the disk mounting surface 10d was formed in resin was demonstrated in the said embodiment, the disk mounting surface 10d has become the lower surface of the disk D by the pressure from the disk D. It is also possible to form the area | region containing at least the disk mounting surface 10d of the hub part 10 from another material, so long as it deform | transmits and mimics (contact surface d1).

Alternatively, the disk mounting surface 10d or its peripheral shape can be appropriately designed such that the disk mounting surface 10d is deformed to mimic the lower surface D1.

As a means for introducing the disk D into the disk mounting surface 10d while maintaining a high right angle with respect to the shaft portion 2 (rotating shaft), for example, a hub portion fitted into the hole D2 of the disk D is used. Means for increasing the precision (coaxiality or cylinder degree with respect to the rotating shaft, etc.) of the cylindrical surface 10e of (10), and improving the fixing precision with respect to the hub part 10 of the clamper 13 to which the disk D is fitted. Various means including a means can be employ | adopted.

In the above embodiment, the magnetic disk drive device represented by the HDD is exemplified. However, the present invention relates to an optical disk drive device such as CD-ROM, CDR / RW, DVD-ROM / RAM, and magneto-optical disk drive such as MD and MO. Applicable to devices and the like.

Moreover, in the said embodiment, although the case where the hub part 10 was injection-molded integrally with the shaft member 2 by the injection molding of resin which uses the metal shaft member 2 as an insertion part was demonstrated, for example, the hub part 10 ) Can be integrated by injecting the end of the metal shaft member 2 formed separately from the hub portion 10 into a hole formed in the center of the hub portion 10 after injection molding only of the resin part. Alternatively, the shaft member 2 may be made of resin, and both the hub portion 10 and the shaft member 2 may be integrally molded by injection molding of resin.

Moreover, in the said embodiment, the thrust bearing part (between the upper end surface 2b1 of the flange part 2b and the lower end surface 8b of the sleeve part 8, and between the hub part 10 and the housing part 9, respectively) Although the case where T1, T2 is provided was demonstrated, this invention is applicable regardless of the formation location of thrust bearing part T1, T2. That is, whether or not the bottom surface 10a1 of the hub portion 10 forms a thrust bearing clearance is not a problem. For example, although not illustrated, all of the thrust bearing portions T1 and T2 are formed of the flange portion 2b. It may be formed between both end faces and faces opposing these faces.

In addition, the component parts of the fluid bearing apparatus 1 except the hub part 10 and the shaft member 2 need not be limited to the said embodiment. For example, although not shown, the present invention also relates to the integration between the components, such as integrally forming the housing portion 9 and the sleeve portion 8 with the same material (unitizing the bearing member 7). Can be applied.

In addition, in the above embodiment, although the radial bearing part R1, R2 and thrust bearing part T1, T2 illustrate the structure which produces the dynamic pressure action of a lubricating oil by a herringbone shape or a spiral shaped dynamic pressure groove, The invention is not limited to this.

For example, as the radial bearing portions R1 and R2, although not shown, a so-called step-shaped dynamic pressure generating portion in which axial grooves are formed at plural portions in the circumferential direction or a plurality of circular arc surfaces are arranged in the circumferential direction. A so-called multi-arc bearing may be employed in which a wedge-shaped radial gap (bearing gap) is formed between the opposing cylindrical outer peripheral surface 2a of the shaft member 2.

Alternatively, the inner circumferential surface 8a of the sleeve portion 8 is a cylindrical outer circumferential surface which does not form a dynamic pressure groove, an arc surface, or the like as the dynamic pressure generating portion, and a cylindrical outer circumferential surface of the shaft member 2 facing the inner circumferential surface 8a ( 2a), so-called cylindrical bearings can be constructed.

In addition, although one or both of the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 are not shown similarly, the area | region where the dynamic pressure generation part is formed (for example, the lower end surface 8b of the sleeve part 8b). ), So-called step bearings or corrugated bearings (step-shaped waveforms) formed with a plurality of radial groove-like dynamic pressure grooves at predetermined intervals in the circumferential direction on the upper end surface 9a) of the housing part 9. It can also be configured.

Moreover, in the above embodiment, the radial dynamic pressure generating part (dynamic pressure grooves 8a1 and 8a2) is further provided on the sleeve part 8 side, and the thrust dynamic pressure generating part (at the side of the sleeve part 8 and the housing part 9). Although the case where the dynamic pressure grooves 8b1 and 9a1) are formed respectively has been described, the area in which these dynamic pressure generating portions are formed is, for example, the outer circumferential surface 2a of the shaft member 2 facing them or the upper end surface of the flange portion 2b ( 2b1) or the lower end surface 10a1 side of the hub part 10 may be formed.

In addition, in the above description, although the lubricating oil was illustrated as the fluid which fills the inside of the fluid bearing apparatus 1, and forms a lubricating film in a radial bearing clearance and a thrust bearing clearance, besides, a lubricating film is formed in each bearing clearance. A fluid which can be used, for example, a gas such as air, a lubricant having fluidity such as a magnetic fluid, or a lubricating grease may be used.

Claims (10)

A shaft member, a hub portion integrally or separately provided to the shaft member, and a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member to support the shaft member to be rotatable in the radial direction. In a fluid bearing device with a radial bearing part: The hub portion is formed of a resin, and the hub portion exhibits a resin orientation in the radial direction over its entire circumference. A shaft member, a hub portion integrally or separately provided to the shaft member, and a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member to support the shaft member to be rotatable in the radial direction. In a fluid bearing device with a radial bearing part: The hub portion is injection molded with resin, and an annular gate mark is formed on the hub portion by injection molding. The fluid bearing device according to claim 2, wherein the hub portion has a disk mounting surface, and the gate mark is formed in the vicinity of the disk mounting surface. A shaft member, a hub portion integrally or separately provided to the shaft member, and a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member to support the shaft member to be rotatable in the radial direction. In the method of manufacturing a fluid bearing device having a radial bearing portion: An injection molding process of injection molding the hub portion with a resin; In the injection molding step, an annular gate is formed in a molding die of the hub portion, and a molten resin is filled in the cavity from the annular gate. 5. The method of manufacturing a fluid bearing device according to claim 4, wherein said annular gate having different gate widths in the circumferential direction is used. A shaft member, a hub portion integrally or separately provided to the shaft member, and a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member to support the shaft member to be rotatable in the radial direction. A fluid bearing device having a radial bearing portion and a yoke made of a magnetic material and adhesively fixed to the hub portion, the fluid bearing device comprising: And the hub portion is injection molded with resin, and the gate mark formed on the hub portion by the injection molding is blocked by an adhesive supplied to the adhesive fixing surface of the hub portion and the yoke. 7. A fluid bearing device according to claim 6, wherein said gate mark is on an adhesive fixed surface with said yoke. A shaft member, a hub portion integrally or separately provided to the shaft member, and a lubricating film of fluid generated in the radial bearing gap facing the outer circumferential surface of the shaft member to support the shaft member to be rotatable in the radial direction. In a method of manufacturing a fluid bearing device having a radial bearing portion and a yoke made of a magnetic material and adhesively fixed to the hub portion: An injection molding step of injection molding the hub part with a resin, and an adhesive fixing step of adhesively fixing the yoke to the hub part formed in the injection molding step; And in the adhesive fixing step, the adhesive is solidified in a state in which the gate mark formed by injection molding of the hub portion is blocked by an adhesive supplied to the adhesive fixing surface of the hub portion and the yoke. Manufacturing method. A rotating member having a shaft portion and a hub portion integrally or separately provided with the shaft portion, and non-contactably rotatable in the radial direction by the dynamic pressure action of a fluid generated in a radial bearing gap facing the outer circumferential surface of the shaft portion. A dynamic pressure bearing device having a supporting radial bearing portion; A disk in contact with the disk mounting surface of the hub portion and fixed by a predetermined clamping force; And In the disk drive device having a motor unit for rotationally driving the rotating member mounted with the disk: And the disk mounting surface is deformed to mimic the contact surface of the disk by the clamping force. 10. The disk drive apparatus according to claim 9, wherein a region including the disk mounting surface is formed of a resin.

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